/*
 * Copyright (C) 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.emay.sdk.util.json.gson.internal.bind;

import java.io.IOException;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.ParsePosition;
import java.util.Date;
import java.util.Locale;

import cn.emay.sdk.util.json.gson.Gson;
import cn.emay.sdk.util.json.gson.JsonSyntaxException;
import cn.emay.sdk.util.json.gson.TypeAdapter;
import cn.emay.sdk.util.json.gson.TypeAdapterFactory;
import cn.emay.sdk.util.json.gson.internal.bind.util.ISO8601Utils;
import cn.emay.sdk.util.json.gson.reflect.TypeToken;
import cn.emay.sdk.util.json.gson.stream.JsonReader;
import cn.emay.sdk.util.json.gson.stream.JsonToken;
import cn.emay.sdk.util.json.gson.stream.JsonWriter;

/**
 * Adapter for Date. Although this class appears stateless, it is not.
 * DateFormat captures its time zone and locale when it is created, which gives
 * this class state. DateFormat isn't thread safe either, so this class has to
 * synchronize its read and write methods.
 */
public final class DateTypeAdapter extends TypeAdapter<Date> {
	public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
		@SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
		@Override
		public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
			return typeToken.getRawType() == Date.class ? (TypeAdapter<T>) new DateTypeAdapter() : null;
		}
	};

	private final DateFormat enUsFormat = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.US);
	private final DateFormat localFormat = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT);

	@Override
	public Date read(JsonReader in) throws IOException {
		if (in.peek() == JsonToken.NULL) {
			in.nextNull();
			return null;
		}
		return deserializeToDate(in.nextString());
	}

	private synchronized Date deserializeToDate(String json) {
		try {
			return localFormat.parse(json);
		} catch (ParseException ignored) {
		}
		try {
			return enUsFormat.parse(json);
		} catch (ParseException ignored) {
		}
		try {
			return ISO8601Utils.parse(json, new ParsePosition(0));
		} catch (ParseException e) {
			throw new JsonSyntaxException(json, e);
		}
	}

	@Override
	public synchronized void write(JsonWriter out, Date value) throws IOException {
		if (value == null) {
			out.nullValue();
			return;
		}
		String dateFormatAsString = enUsFormat.format(value);
		out.value(dateFormatAsString);
	}

}
